﻿using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Runtime.Remoting.Messaging;
using System.Text;
using System.Threading.Tasks;
using System.Web;

namespace SlamDunk.CMS.Common
{
    /// <summary>
    /// 验证码处理类
    /// </summary>
    public class ValidCode
    {
        #region 00.静态当前上下文对象属性 Current
        /// <summary>
        /// 将构造函数私有化
        /// </summary>
        private ValidCode() { }

        /// <summary>
        /// 当前ValidCode实例
        /// </summary>
        public static ValidCode Current
        {
            get
            {
                //从线程缓存中取，如果没有new一个，然后再存入线程缓存
                ValidCode validCode = CallContext.GetData(typeof(ValidCode).Name) as ValidCode;
                if (validCode == null)
                {
                    validCode = new ValidCode();
                    CallContext.SetData(typeof(ValidCode).Name, validCode);
                }
                return validCode;
            }
        }
        #endregion

        #region 01.验证码的最大长度属性
        /// <summary>
        /// 验证码的最大长度属性
        /// </summary>
        public int MaxLength
        {
            get { return 10; }
        }
        #endregion

        #region 02.验证码的最小长度属性
        /// <summary>
        /// 验证码的最小长度属性
        /// </summary>
        public int MinLength
        {
            get { return 1; }
        }
        #endregion

        #region 03.创建验证码字符串方法
        /// <summary>
        /// 创建验证码字符串方法
        /// </summary>
        /// <param name="length">验证码长度</param>
        /// <returns>验证码字符串</returns>
        public string CreateValidCode(int length)
        {
            int[] randMembers = new int[length];
            int[] validateNums = new int[length];
            string validateNumberStr = string.Empty;
            //生成起始序列值
            int seekSeek = unchecked((int)DateTime.Now.Ticks);
            Random seekRand = new Random(seekSeek);
            int beginSeek = (int)seekRand.Next(0, Int32.MaxValue - length * 10000);
            int[] seeks = new int[length];
            for (int i = 0; i < length; i++)
            {
                beginSeek += 10000;
                seeks[i] = beginSeek;
            }
            //生成随机数字
            for (int i = 0; i < length; i++)
            {
                Random rand = new Random(seeks[i]);
                int pownum = 1 * (int)Math.Pow(10, length);
                randMembers[i] = rand.Next(pownum, Int32.MaxValue);
            }
            //抽取随机数字
            for (int i = 0; i < length; i++)
            {
                string numStr = randMembers[i].ToString();
                int numLength = numStr.Length;
                Random rand = new Random();
                int numPosition = rand.Next(0, numLength - 1);
                validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));
            }
            //生成验证码
            for (int i = 0; i < length; i++)
            {
                validateNumberStr += validateNums[i].ToString();
            }
            return validateNumberStr;
        }
        #endregion

        #region 04.创建验证码图片方法——直接输出到浏览器
        /// <summary>
        /// 创建验证码图片——直接输出到浏览器
        /// </summary>
        /// <param name="validCode">验证码字符串</param>
        /// <param name="context">HttpContext上下文对象</param>
        public void CreateValidCodeImage(string validCode, HttpContext context)
        {
            Bitmap image = new Bitmap((int)Math.Ceiling(validCode.Length * 12.0), 22);
            Graphics g = Graphics.FromImage(image);
            try
            {
                //生成随机生成器
                Random random = new Random();
                //清空图片背景色
                g.Clear(Color.White);
                //画图片的干扰线
                for (int i = 0; i < 25; i++)
                {
                    int x1 = random.Next(image.Width);
                    int x2 = random.Next(image.Width);
                    int y1 = random.Next(image.Height);
                    int y2 = random.Next(image.Height);
                    g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
                }
                Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
                 Color.Blue, Color.DarkRed, 1.2f, true);
                g.DrawString(validCode, font, brush, 3, 2);
                //画图片的前景干扰点
                for (int i = 0; i < 100; i++)
                {
                    int x = random.Next(image.Width);
                    int y = random.Next(image.Height);
                    image.SetPixel(x, y, Color.FromArgb(random.Next()));
                }
                //画图片的边框线
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                //保存图片数据
                MemoryStream stream = new MemoryStream();
                image.Save(stream, ImageFormat.Jpeg);
                //输出图片流
                context.Response.Clear();
                context.Response.ContentType = "image/jpeg";
                context.Response.BinaryWrite(stream.ToArray());
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }
        #endregion

        #region 05.创建验证码图片方法——返回字节数组
        /// <summary>
        /// 创建验证码图片方法——返回字节数组
        /// </summary>
        /// <param name="validCode">验证码字符串</param>
        /// <returns>验证码图片序列化后的字节数组</returns>
        public byte[] CreateValidCodeImage(string validCode)
        {
            Bitmap image = new Bitmap((int)Math.Ceiling(validCode.Length * 12.0), 22);
            Graphics g = Graphics.FromImage(image);
            try
            {
                //生成随机生成器
                Random random = new Random();
                //清空图片背景色
                g.Clear(Color.White);
                //画图片的干扰线
                for (int i = 0; i < 25; i++)
                {
                    int x1 = random.Next(image.Width);
                    int x2 = random.Next(image.Width);
                    int y1 = random.Next(image.Height);
                    int y2 = random.Next(image.Height);
                    g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
                }
                Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
                 Color.Blue, Color.DarkRed, 1.2f, true);
                g.DrawString(validCode, font, brush, 3, 2);
                //画图片的前景干扰点
                for (int i = 0; i < 100; i++)
                {
                    int x = random.Next(image.Width);
                    int y = random.Next(image.Height);
                    image.SetPixel(x, y, Color.FromArgb(random.Next()));
                }
                //画图片的边框线
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                //保存图片数据
                MemoryStream stream = new MemoryStream();
                image.Save(stream, ImageFormat.Jpeg);
                //输出图片流
                return stream.ToArray();
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }
        #endregion

        #region 06.根据验证码长度计算验证码图片宽度方法
        /// <summary>
        /// 根据验证码长度计算验证码图片宽度方法
        /// </summary>
        /// <param name="validCodeLength">验证码长度</param>
        /// <returns>验证码图片宽度</returns>
        public static int GetImageWidth(int validCodeLength)
        {
            return (int)(validCodeLength * 12.0);
        }
        #endregion

        #region 07.计算验证码图片宽度方法
        /// <summary>
        /// 计算验证码图片宽度方法
        /// </summary>
        /// <returns>验证码图片宽度</returns>
        public static double GetImageHeight()
        {
            return 22.5;
        }
        #endregion
    }
}
